As of right now every time I split an event adjustment with an already added FX it will turn the preview into a black screen from the split point forward, with seemingly no way to fix it on the new Vegas Pro 21 (300)
EDIT: Strangely, undoing (ctrl-z) and redoing (ctrl-shift-z) the split fixes the problem and the preview screen isn't a black screen anymore. Also this black screen bug only happens on the preview, the render comes out completely fine.
I'm at a loss at what could be causing this as I'm wondering if it is just me or anyone using the new build, if anyone could kindly test this too it would help a lot